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Why oceans on Mars have proved so elusive

OCEANS on Mars would have been acidic, a new analysis of the planet’s chemistry suggests. This could explain why scientists have failed to clinch the case for Martian oceans, despite NASA’s rovers finding evidence of water on the planet.

On Earth, oceans absorb carbon dioxide from the atmosphere and deposit it as carbonate rock. Scientists have looked for, but failed to find, similar deposits on Mars. Now Alberto Fairen from the Autonomous University of Madrid (UAM) in Spain and colleagues have shown why Martian oceans would not have formed carbonates.